Beam steering of antennas is employed in a number of applications in order to change the direction of the main lobe of a radiation pattern. For example, antennas that employ beam steering are utilized by radio systems including those deployed in mobile telephony applications, such as the antennas that support communication between base stations and other network equipment and the user equipment. In this regard, the antennas that support radio frequency (RF) communication in radio systems may be phased array antennas that include a plurality of antenna elements. The relative phases of the RF signals driving the various antenna elements may be controlled in order to effectively steer the direction of the main beam of the radiation pattern of the phased array antennas.
In order to steer an antenna, the antenna may include or be associated with a phase shifter. For a phased array antenna, the antenna includes a plurality of phase shifters, one of which is associated with each antenna element. The performance of the antenna is dependent upon the accuracy with which the main lobe is steered, such as the accuracy with which a phase shifter steers the respective antenna element. In this regard, the quality of the radiation pattern of a phased array antenna is the result of accurate phasing of the individual antenna elements of the phased array antenna.
The phase shift to be provided by a phase shifter may be predefined based upon the specifications according to which the antenna is to be manufactured and the anticipated antenna performance. However, variations during the manufacture of the various components of the antenna including the thickness of the metal traces, the thickness of the printed circuit boards and/or the variation in quality and composition of the materials from which the antenna is constructed, the size of various components of the antenna and the like, may cause the performance of the antenna to deviate, at least slightly, from the anticipated antenna performance. As such, a phase shifter may be calibrated in order to provide the predefined phase shift such that the antenna may continue to provide the desired beam steering even though the manufacture of the antenna may have deviated slightly from the specifications. The calibration of a phase shifter may be performed during or immediately following manufacture of the antenna or during initial installation of the antenna.
The calibration of a phase shifter may require extensive testing of the antenna and, as a result, may be time consuming. For a phased array antenna having a plurality of antenna elements and a plurality of phase shifters, one of which is associated with each antenna element, the calibration process may be more extensive as each phase shifter must be individually calibrated. The time required for the calibration of the phase shifters of an antenna array is further increased for dual polarized antennas in which each antenna element is associated with two phase shifters, one for each polarization. As such, the calibration of the phase shifters of an antenna array as required to ensure the antenna performs as intended may be more time consuming than desired.